In U.S. Provisional Application No. 60/663,503, titled as “Monolithic Microchip Laser With Intracavity Beam Combining And Sum Frequency Or Difference Frequency Mixing”, Luo, Zhu, and Lu have disclosed a low-noise monolithic microchip laser, wherein intracavity beam combining and sum frequency mixing (SFM) or difference frequency mixing (DFM) are used for generation of various lasing wavelengths. According to their invention, two fundamental laser beams are generated from two lasing media pumped by two laser diodes in an integrated dual laser cavity. These two fundamental laser beams are then combined in an intracavity birefringence crystal based on the walk-off effect to generate the desired wavelength by means of intracavity SFM or DFM in a nonlinear optical (NLO) crystal.
One of the advantages of the monolithic microchip laser is compact size. There still remain rooms for improvement, however. Since the walk-off angle is a function of the birefringence and the cut angle, a reduction in the separation of the pump diodes will proportionally reduce the length of the birefringence crystal, and consequently, the device size. This is the issue that will be addressed in the present invention.